1. Field of the Invention
The present invention relates to an optical module formed by a package for receiving and emitting light and an optical connector, and more particularly, to the improvement of a coupling structure between the package and the optical connector and its manufacturing method.
2. Description of the Related Art
Optical interconnection of the LSI packages with each other by optical fibers or optical waveguides is attractive in order to enhance thee operation speed in a computer system where large scale integrated circuit (LSI) packages such as a central processing unit (CPU) and memories are mounted on a board.
Connecting the LSI packages with each other by using optical interconnection modules is one of possible way to establish inter-LSI package optical interconnection. In this configuration, however, the redundant portions of the optical fibers would need to be processed. Because the most of optical interconnection module have pig-tailed optical fibers of normalized length and these fibers are not detachable from the module. To avoid the optical fiber occupation on the board, it is preferable that the optical fibers are removable from the optical module. By this, optical modules are connected each other by optical fibers of preferable lengths.
Optical modules without pig-tailed optical fibers have been suggested. That is, optical fibers are removable from LSI packages, In this case, if the optical fibers are moved in the horizontal direction to couple with the LSI packages, dead space due to the horizontal motion of the optical fibers may be created on a board, so that the mounting density of LSI packages on the board is decreased. Therefore, it is preferable that the optical fibers be moved in the vertical direction to couple with the LSI packages.
In a first prior art optical module (see: JP-A-4-308804), an array of optical fibers adhered to a microlens array is moved down to couple with an LSI package, so that the above-mentioned dead space on a board is decreased to increase the mounting density of LSI packages on the board. This will be explained later in details
In the above-described first prior art optical module, however, if the alignment of the optical fibers to the LSI package fluctuates, the coupling efficiency therebetween deteriorates.
In a second prior art optical module (see: JP-A-10-115732), an optical fiber with a mirror and a half mirror is moved down to couple with a package. This also will be explained later in detail.
In the above-described second prior art optical module, however, since the mirror and the half mirror are protruded from the bottom surface of the optical fiber, the coupling between the optical fiber and the package is carried out by a transparent adhesive layer, so that it is impossible to remove the optical fiber from the package. Thus, the optical fiber is not removable. If the optical fiber is forcibly removed from the package and is again fixed to the package or another package, the coupling loss fluctuates.